Advertisement "XXX" from site "XXX" was rejected because the client's platform is not supported.

Hi

I'm advertising an OSD task sequence to some scale devices and getting the following issue:

Advertisement "XXXXXXXX" from site "XXX" was rejected because the client's platform is not supported.

Possible cause: The client received the advertisement but rejected it because the client's platform was not included in the list of supported platforms specified for the program.
Solution: If the client should actually accept the advertisement, either disable supported platform checking or modify the list of supported platforms specified on the Requirements tab of the Program's Properties dialog box. Changes to the program properties will not be detected until the list of advertised programs is refreshed on the client.

The question below looked like the same as my issue:

http://social.technet.microsoft.com/Forums/systemcenter/en-US/9b500cf2-8d78-45a5-a0e1-8fc4f1e79c9e/osd-advertisement-rejected-by-client

However it is clear there that he has selected a specific platform whereas my TS is set to run on any platform. So why would it be causing this problem?

The clients I am advertising to are XPe and currently have the old SMS clients (v2.5). However in sitemode,This site contains only ConfigMgr 2007 clients is notchecked so my understanding is that there shouldn't be any issue with receiving OSD policy / advertisements for these machines. 

Thanks in advance for any help